Once the fallout from Deflategate dies down the NFL will have to again face the issue of head trauma in its players. On Friday another reminder of just how significant repeated blows to the head are to the long-term health of players came in a concerning report published by PBS’s Frontline.

The report, conducted by Boston University and Department of Veterans Affairs researchers and released on Friday, said that 87 of 91 former NFL players examined tested positive for chronic traumatic encephalopathy or CTE. The degenerative condition, which has been linked to early onset Alzheimer’s and dementia, is often considered a factor in the mental deterioration of former players.

I’ve written about CTE and Ann McKee’s research several times. Care must be taken here since there is likely selection bias in the post-mortem examinations of the player’s brains. Many players who thought they might be suffering from CTE donated their brains. Those who feel they are healthy are unlikely to donate.

But, even so, the fact that such a high percentage of players who felt they were suffering from brain trauma actually were is extremely worrisome.

Lately, I’ve tried to break it down,” Turley said. “I remember, every season, multiple occasions where I’d hit someone so hard that my eyes went cross-eyed, and they wouldn’t come uncrossed for a full series of plays. You are just out there, trying to hit the guy in the middle, because there are three of them. You don’t remember much. There are the cases where you hit a guy and you’d get into a collision where everything goes off. You’re dazed. And there are the others where you are involved in a big, long drive. You start on your own five-yard line, and drive all the way down the field—fifteen, eighteen plays in a row sometimes. Every play: collision, collision, collision. By the time you get to the other end of the field, you’re seeing spots. You feel like you are going to black out. Literally, these white explosions—boom, boom, boom—lights getting dimmer and brighter, dimmer and brighter.

It’s likely not the concussions peruse but the constant, repetitive sub concussive strikes. It is likely why so many of these people are lineman. It is why boxers get it too. Rugby, soccer and lactose do not feature this. There may also be an enhancement effect when taking steroids.